The latest research on brain trauma and young athletes

This article discusses many different studies done on young athletes and concussions done recently.

First the good news: There's little to no evidence that the average high school athlete faces a scenario similar to former professional football players who exhibit signs of serious depression or early-onset dementia linked to their years on the playing field.

"We're not seeing an epidemic of men in their early 50s with early Alzheimer's because they played high school football," said Steven Broglio, director of the Neurotrauma Research Laboratory at University of Michigan.

But new research conducted by Broglio and others around the country now shows troubling evidence that high school football and other contact sports can take a more subtle long-term toll on the brain -- and it's not just concussions that are problematic.

In fact, for all the focus on concussions, the bigger worry for athletes may be the accumulation of body blows that jolt the head, shaking the brain like a bowl of Jello and traumatizing fragile brain tissue and nerves.

The issue is especially worrisome in football, a sport built around plays where athletes slam into each other as hard as possible. Football players can experience as many as 1,000 impacts or more over the course of season. Researchers say that, in terms of g-forces and stress on the body, playing in a high school football game is comparable to being in a 20- or 30-mph car crash.

Those so-called sub-concussive impacts may not cause concussions, but it appears they can add up and result in damage to the brain.

Broglio and his colleagues at U-M recently published a study that looked at college students with and without a history of concussions. There were no outward differences between the two groups. But on close examination, the students with histories of concussions showed changes in gait, balance and in the brain's electrical activity, specifically attention and impulse control.  

In a U-M press release on the study, Brolgio offered this analogy: 

The signaling pathways in our brains are analogous to a five-lane highway. On a new highway, traffic runs smoothly and quickly as all lanes are in top shape. However, during normal aging, the asphalt deteriorates and lanes might become bumpy or even unusable. Traffic slows.

Similarly, our brains start with all pathways clear to transfer electrical signals rapidly. As we age, the brain's pathways break down and can't transfer the information as quickly. Concussive and other impacts to the head may result in a 'pothole' on the brain's highway, causing varying degrees of damage and speeding the pathway's natural deterioration.

"These are all very high-functioning college students," Broglio said about the subjects in the study with a history of concussion. "But on a very subtle level, something has changed. It appears that because of concussive or sub-concussive blows, there has been a permanent change in the brain and as they grow older, this could magnify."

In short, he said, it's possible that the changes could speed up the memory problems and other mental deterioration that people experience as they age. 

'Totality of blows'

Meanwhile at Purdue University, researchers studied the issue of sub-concussive blows by putting sensors in the helmets of Lafayette, Ind., high school football players for two seasons. 

Their conclusion: Concussions are likely caused by many hits over time and not from a single blow to the head, as commonly believed.

"The most important implication of the new findings is the suggestion that a concussion is not just the result of a single blow, but it's really the totality of blows that took place over the season," Eric Nauman, an associate professor of mechanical engineering and an expert in central nervous system and musculoskeletal trauma, said in a press release about the study. "The one hit that brought on the concussion is arguably the straw that broke the camel's back."

The Purdue researchers had additional findings contrary to conventional thinking.

"Most clinicians would say that if you don't have any concussion symptoms you have no problems," Larry Leverenz, an expert in athletic training and a clinical professor of health and kinesiology, said in the press release. "However, we are finding that there is actually a lot of change, even when you don't have symptoms."

In the two seasons studied, there were six players with concussions but 17 that showed brain changes even though they did not have concussions. 

Players in the study received from 200 to nearly 1,900 hits to the head in a single season. Helmet-sensor data indicated impact forces to the head ranged from a g-force of 20 to more than 100. The worst hit was almost 300 g.

Nauman said that a person in a 30 mph car crash experiences a g-force of 30 if he/she is wearing a seatbelt and 150 without a seatbelt.  

"The average hit we record is about 22 Gs,' Nauman said about the Lafayette football players. "So it's not that different (from a car crash). It is not uncommon for a player to  have one 80-100 G hit, a couple of 50-60s and a bunch of smaller ones."

The Purdue research mirrors the findings of a similar study at the University of Rochester Medical Clinic in upstate New York, where high school football and hockey players showed changes in their brain scans even when they hadn't experienced a concussion.

That study involved nine athletes and six people in a control group. Among the nine athletes, only one was diagnosed with a sports-related concussion, but six others showed abnormalities on their post-season scans that were closer to the concussed brain than to the normal brains in the control group.

The brain scans also correlate to the number of head hits and symptoms experienced, the researchers said.

No clear answers
So what's the take-away message for parents and athletes about the research?

First, Broglio stressed that brain function is affected by many factors, including genetics and lifestyle choices such as smoking and alcohol consumption.

"Concussion may be only one small factor," he said.

He also pointed out higher risk factors are just that: Not every cigarette smoker gets lung cancer, not every blonde with a history of sunburns gets skin cancer, people with a family history of heart disease  may or may not  have heart problems.

In addition, Broglio stressed that the brain research on the young athletes is still in its infancy.

"It's not entirely clear" if and how the brains of young athletes are affected by the sports they play, Broglio said. "We are realizing it's probably not how many concussions you have that makes a difference, but the total exposure" to concussive and sub-concussive impacts.

He added that it appears that playing contact sports in high school is a "very small risk" in terms of overall long-term health.

But, he acknowledged, at what point contact sports becomes too risky for teenagers is a "very big question. We don't have clear answers."

For that reason, Dr. Robert Baker, a family practitioner with Bronson Orthopedics & Sports Medicine in Kalamazoo, said one of the biggest challenges for doctors who treat sports-related concussions is recommending if and when a youngster should end his or her sports career.

"The best we can do is look at the type of hits they've experienced, the periods of recovery," Baker said. Determining the threshold where enough is enough "is a very difficult issue."

But Baker and other local doctors say it rarely gets to that point, and it's important for parents to keep the risk of sports-related concussions in context.

"You're more at risk by not wearing a seatbelt," said Dr. James VanHuysen, of Bronson Orthopedics & Sports Medicine.

Dr. Daniel Fain, of Kalamazoo's Bronson Pediatric Neurology, agreed.

"I think sports are important," he said, and fear of sports-related concussions shouldn't keep kids out of sports.

That said, "parents need to understand the severity of concussions" so that when they do occur, families respond appropriately, he said. "If I were a parent, I'd hope my kid would be looking at this."

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